Worm



Filed May 9. 1942 I 2 Sheets-Sheet 1 enna.

w. J. STUBER ET AL I 2,310,880 V Feb. 9, 1 943.

- w. J. .STUBER ETAL 310,880

WORM

Filed May 9, 1942 2 Sheets-Sheet 2 v 4 77 v 2/ 6' v 20 65 A9 Patented Feb. 9, 1943 WORM Walter J. Stuber and John J. Di Ienno, Philadelphia, Pa., assignors to Carey McFall Company, Philadelphia, Pa., a corporation of Pennsylvania Application May 9, 1942, Serial No. 442,316

8 Claims.

This invention relates to a tilting device for use, particularly, in a Venetian blind, for tilting the slats to any desired angle within a range of substantially 180 with respect to the central plane of the hanging blind,

Prior to the present invention, the worms normally used in the majority of Venetian blinds, have been in the form of machine-cut screws turned out of bar stock, or of pressed sheet steel construction requiring the use of costly dies.

The primary object of the present invention is to provide a highly efiicient simple and inexpensive worm structure requiring no lathe or die work and which can be assembled at a minimum of cost and labor.

Other features of the invention, the construction, mode of assembly, and the operation of the device will be more fully disclosed hereinafter, reference being had to the accompanying drawings of which:

Fig. 1 illustrates a Venetian blind embodying a tilting mechanism constructed and assembled in accordance with the principles of the present invention;

Fig. 2 is a sectional elevation taken on the line 22, Fig. 1;

Fig. 3 is an end view of the tilting mechanism shown in Fig. 2;

Fig. 4 is a sectional elevation taken on the line 4-4, Fig. 2;

Fig. 5 is a detached perspective view of the elements constituting the worm and driving means for the tilting mechanism;

Fig. 6 is a perspective view of the worm wheel;

Fig. 7 is a perspective view of the bracket which supports the worm and worm wheel mechanism of Figs. 5 and 6; and

Fig. 8 is an enlarged fragmentary sectional view of the intermeshing portions of the worm and worm wheel.

As shown in Fig. l, the Venetian blind includes a head rail l which is normally supported by head rail brackets 2 and 3. These brackets are normally fastened to the frame or inside trim 4 of a window or other opening 5 which is to be closed by the blind Ill.

The head rail is provided with depending brackets 6 and I which pivotally support the tilt rail 8 of the blind [8. One end of the tilt rail 8 is provided with a trunnion II, which is rotat- K ably mounted in the bracket '1. The opposite end of the tilt rail 8 is provided with an axial projection I2, which projects into an opening l3 formed in an axial extension l4 of the worm wheel l5.

The worm wheel I5 is freely rotatably mounted on a shouldered rivet |6 which is secured in the bracket 6, said rivet It being axially aligned with the trunnion I by which the first said end of the tilt rail 8 is rockably supported in the bracket 1.

The bracket 6 is provided with a central opening H. The opposite sides of the opening ll are respectively provided with axially aligned bearings l8, l8 for rotatably supporting the operating shaft I!) of the tilting device at right angles to the axis of the tilt rail 8, trunnion H, and rivet I6. Frictionally secured to the operating shaft l9, within the opening ll, between the bearings |8, I8, is the worm which meshes with the teeth of the worm wheel l5.

In the present instance, the worm 20 is formed of a plurality of spiral convolutions 2|, 2| of a coil spring. The spring convolutions 2|, 2| frictionally embrace and tightly grip the external surface of a tubular hub sleeve 22. The leeve 22 is provided with a longitudinal slot 23, formed in one side solely thereof. The spiral convolutions 2|, 2| of the spring wire 26 constitute the normal spiral thread of the worm and mesh with the teeth 5 of the tilting worm wheel l5.

The teeth of the worm wheel l5 (Fig. 8) are formed in such a manner that the broadest part of each tooth 25, i. e., that part lying along the circular pitch line x--:c of the worm wheel I5, engages the spring wire 25, of which the convolutions 2|, 2| are composed, at diametrically opposite points only on said wire.

The gullets or spaces 2'! between the teeth are sufficiently deep to provide clearance 22, at all times, between the outer peripheral surfaces of the convolutions 2| and the bases of the teeth recesses 21. Due to the circular cross section of the spring wire 28, clearances 23, 29 are formed at each side of each convolution 2| of the worm, between the pitch line y--y of the worm and the external surface of the sleeve 23 for the outer ends or points of the teeth 25.

By the above construction, a minimum amount of contact between the edges of the teeth 25 of the worm wheel I5 and the circular surfaces of the convolutions 2| of the worm 20 is present at all times, consequently a minimum of friction is produced which enables the tilting mechanism to be operated with a minimum of effort.

In the present instance, a circumferentially grooved cord or ball-chain pulley or sheave 30 is secured to one end of a worm shaft I9, and a cord guide 3%, forming no part of the present invention, is loosely mounted on the hub 32 of the sheave, between one side of the sheave 30 and an outer bearing 33 formed on the adjacent outer side of the bracket 6. A corresponding outer bearing 33 is formed on the opposite side of the bracket 6, making the bracket symmetrical for use with the sheave 30 at either side of the bracket, in either a right or left hand blind.

The worm and worm wheel construction of the present invention is such that continued rotation of the worm 2B, in either direction, will run one of the ends 26a or 2th of the spring wire 26, of which the series of convolutions 2 I, 2| are formed, out of mesh with the last tooth 25a or 251) on either side of the worm wheel i5, whereby adjustment of the tassels or other ornaments at the ends 35, 25 of the tilting cord 3-4, which passes around the sheave 35, may be effected, should said ends of the cord get out of balance, i. e, become long and short respectively, as a result of slippage of the cord over and around the sheave 3t. Reverse rotation of the worm 22 will reengage the worm with the worm Wheel after the cord adjustment has been completed.

As shown in Fig. 5, one end of the split sleeve 22 is slightly belled or flared, at 22a, to receive the end lfia of the worm shaft 19 in assembling the parts of the tilting mechanism. The normal outside diameter of the split sleeve 22 is slightly greater than the inside diameter of the convolutions 2! of the spring wire 2%. By slightly contracting the sleeve 22 radially the normal end 2222 of the sleeve may be readily slipped, axially, into the convolutions 2i, 2! of the spring wire 26, after which release of the sleeve will permit it to expand radially into tight non-slipping contact with the internal surfaces of the spring wire convolutions 2!.

The assembled split sleeve hub 22 and spring convolutions 2i, 2! are then placed in the opening I! of the bracket 6, intermediate the bearings I3, is. The worm shaft I3 is then passed through the bearings 33 and 18 at one side of the bracket and the end i911 of said shaft inserted in the flared end 22a of the sleeve 22. Axial pressure applied to the shaft I 9 forces said shaft through the sleeve 22 and effects a slight radial expansion of said sleeve. This ex pansion is opposed by a counteraction of the coils 2! of the spring wire 26. Axial pressure on the worm shaft I 9 is continued until the end lfla thereof passes completely through the sleeve 22 and through the bearings 18 and 33 at the second side of the bracket 6. Thus, the elements [9, 2| and 22 are frictionally held together by the counter radially inward force exerted on the sleeve 22 by the convolutions 2!, 2! of the spring.

We claim:

1. A worm comprising a hub, and a series of spring wire convolutions frictionally embracing said hub by reactionary dynamic torsional force inherently exerted on said hub circumferentially thereof by said convolutions.

2. A worm comprising a hub, and a series of spring wire convolutions frictionally embracing said hub by reactionary dynamic torsional force inherently exerted on said hub circumferentially thereof by said convolutions, the internal diameter of said convolutions being normally smaller than the external diameter of said hub.

3. A worm comprising a hub in the form of a longitudinally split tube, and a series of spring wire convolutions frictionally embracing said hub by reactionary dynamic torsional force inherently exerted on said hub circumferentially thereof by said convolutions.

4. A worm comprising a hub in the form of a longitudinally split tube, and a series of spring wire convolutions frictionally embracing said hub, the internal diameter of said convolutions being normally smaller than the external diameter of said hub tube.

5. A worm comprising a shaft, a tubular hub flared at one end to receive one end of said shaft for press-fitting said hub on said shaft, and a series of spring Wire convolutions frictionally embracing the outside of said hub by reactionary dynamic torsional force inherently exerted on said hub circumferentially thereof by said convolutions.

6. A worm comprising a shaft, a tubular hub split longitudinally and flared at one end to receive one end of said shaft for press-fitting said hub on said shaft; and a series of spring wire convolutions frictionally embracing the outside of said hub.

'7. A worm comprising a shaft, a tubular hub split longitudinally and flared at one end to receive one end of said shaft for press-fitting said hub on said shaft, and a series of spring wire convolutions frictionally embracing the outside of said hub, the internal diameter of said convolutions being normally smaller than the external diameter of said hub.

8. A worm comprising a shaft, a tubular hub split longitudinally and flared at one end to receive one end of said shaft for press-fitting said hub on said shaft, and a series of spring wire convolutions frictionally embracing the outside of said hub, the internal diameter of said convolutions being normally smaller than the external diameter of said hub, and the internal diameter of said hub being normally smaller than the outside diameter of said shaft.

WALTER J. STUBER. JOHN J. DI IENNO. 

